Four Fundamental Forces of the Universe

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Transcript of Four Fundamental Forces of the Universe

EXAMPLESelectricity for television, ipod, etc.compassWhy we don't fall through everything!our body's electrons repeal electrons in other objectFour fundamental forces govern every single interaction in the universe!

photo credit Nasa / Goddard Space Flight Center / Reto StöckliWHAT IS IT? Attractive force between all particles with mass (never repels)GravityTheories that postulate the unification of the strong, weak, and electromagnetic forces are called Grand Unified Theories (often known by the acronym GUTs).

Theories that add gravity to the mix and try to unify all four fundamental forces into a single force are called Superunified Theories. The theory that describes the unified electromagnetic and weak interactions is called the Standard Electroweak Theory, or sometimes just the Standard Model.Uniting theoriesThe Four Forces that Shape Our Universe!

`1. Create an image with at least one example or use of each of the four forces. This image can be drawn, or done on a computer, or a collage. Label the examples with letters on the image.

You will hand in your image at the end of the week.

2. Identify the forces in the images of the other students. (due next week)

To make things easier, you will work in groups, so go to the corner with your number on it and start brainstorming ideas for images.HomeworkA force is a PUSH or PULLon one object by another objectcausing a change in:directionspeed, orshape

Let's start with GRAVITY...What is a force?No gravity in hypothetical place with no mass anywhere.Everywhere else, there is gravity.Back to warm-up: Which direction is the force on a ball after I drop it?GravityWhy doesn't satellite fall to Earth?Back to warm-up: Which direction is the force on the orbiting earth ball?Review of Centripetal ForceHOW STRONG IS IT?Relatively weak (more on that later)RANGE? Infinite rangeEXAMPLESwhy objects falllimits our jumping heightdetermines structure of galaxies and universeInward force on orbiting objectVelocity keeps object from fallingForce prevents objects from going straightPencil indicates a good time to take notesWHAT IS IT? force between electrically charged particles (attracts and repels)ElectromagnetismHOW STRONG IS IT?10^36 times stronger than gravity!RANGE? Infinite rangeBack to warm-up: Which direction is the force on the magnet?Electromagnetismhttp://www.polleverywhere.com/multiple_choice_polls/MTAwNjI1MzU0OAWhich type of force keeps the electron orbiting the proton?What keeps the protons stuck together?EXAMPLESkeeps protons close enough to form bigger atomsresponsible for energy of nuclear powerWHAT IS IT? binds protons and neutronsStrong nuclear forceHOW STRONG IS IT?10^38 times stronger than gravityRANGE? 10^-15 meters (about the size of proton)Quick review

What is the difference between a proton and a neutron?http://www.polleverywhere.com/multiple_choice_polls/LTE1NjcwMDkwMjEEXAMPLESradioactive decay --> carbon datinginitiates hydrogen fusion in starshow we are all made of stardust!WHAT IS IT? changes protons to neutrons and vice versaWeak nuclear forceHOW STRONG IS IT?"only" 10^25 times stronger than gravityRANGE? 10^-18 meters (within proton)Quick review

The weak force does which of the following?

Rank the strength of the four forces:http://www.polleverywhere.com/multiple_choice_polls/MjAyMjUzODI1OAhttp://www.polleverywhere.com/multiple_choice_polls/MjA4MTc0MDAyNAShanna ShakedUCLA Physics Lecturer